EP1443247A1 - Linear actuator comprising a worm gear - Google Patents

Linear actuator comprising a worm gear Download PDF

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Publication number
EP1443247A1
EP1443247A1 EP04000714A EP04000714A EP1443247A1 EP 1443247 A1 EP1443247 A1 EP 1443247A1 EP 04000714 A EP04000714 A EP 04000714A EP 04000714 A EP04000714 A EP 04000714A EP 1443247 A1 EP1443247 A1 EP 1443247A1
Authority
EP
European Patent Office
Prior art keywords
rod
linear actuator
bar
toothing
profile
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP04000714A
Other languages
German (de)
English (en)
French (fr)
Inventor
Carlo Scaravella
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP1443247A1 publication Critical patent/EP1443247A1/en
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H19/00—Gearings comprising essentially only toothed gears or friction members and not capable of conveying indefinitely-continuing rotary motion
    • F16H19/02—Gearings comprising essentially only toothed gears or friction members and not capable of conveying indefinitely-continuing rotary motion for interconverting rotary or oscillating motion and reciprocating motion
    • F16H19/04—Gearings comprising essentially only toothed gears or friction members and not capable of conveying indefinitely-continuing rotary motion for interconverting rotary or oscillating motion and reciprocating motion comprising a rack
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
    • F16H55/02—Toothed members; Worms
    • F16H55/22—Toothed members; Worms for transmissions with crossing shafts, especially worms, worm-gears

Definitions

  • This invention offers a rapid-movement linear actuator of the type comprising a cogwheel connected to motor means which engage a corresponding sliding toothed rod, wherein said rod is cylindrical and has toothing constituted by a helical thread, and said cogwheel has a curved profile so as to adapt to the shape of the rod.
  • the actuator according to the invention is much cheaper to make than known rack-and-pinion actuators, and presents the advantage of quieter operation, the possibility of eliminating play due to wear, and the possibility of manufacturing actuators in which the rod is up to several metres long, again with limited costs.
  • the invention relates to the sector of precision mechanics, and in particular the sector of linear actuators used, by way of example but not of limitation, to control the movements of parts of machines such as a lathe carriage, the movement of workpieces on machine tools and the movement of slides or support surfaces, and in general in all cases in which a workpiece or part of a machine needs to be moved rapidly with a linear movement.
  • linear actuators Numerous types of linear actuators are known, ranging from the simplest, constituted by the classic rack-and-pinion actuator, to the most sophisticated, such as the recirculating ball screw type.
  • Rack-and-pinion actuators are constituted by a rod with toothing on one side which is engaged by the corresponding toothing of a wheel generally driven by an electric motor.
  • the rotation of the wheel controls the slide along the rod, in one direction or the other, of (for example) a carriage on which the wheel is mounted, or controls the movement of the rod along guides.
  • Racks usually have straight teeth, with the lateral teeth inclined; this involves the drawback of considerable noise, unless precision toothing is used, but such toothing would excessively increase the cost of these accessories, which are generally used for inexpensive applications.
  • the recirculating ball screw type of actuator is quieter and more precise, but also much slower, so although they cost more than the rack-and-pinion type, they are unsuitable to control the fast movements of a workpiece.
  • This invention now offers a rapid-movement linear actuator of the type comprising a toothed wheel which engages a rod, also with surface toothing, but wherein the rod is cylindrical and the toothing consists of a simple helical thread engaged by the corresponding toothing of the wheel, which also has a curved profile, so as to adapt to the shape of the rod and provide a larger contact area between the teeth and quieter operation.
  • a rod of this kind can be manufactured simply by threading a cylindrical bar; it can therefore be made rapidly and cheaply even in long lengths, using common machine tools for threading and/or rolling.
  • the actuator according to the invention is substantially constituted by a rod 1, with a helical thread 2 on the surface, which is engaged by the corresponding toothing of a drive wheel 3, which is fitted to a fixed shaft 4 and caused to rotate by a motor not illustrated in the figure.
  • Rod 1 is made simply by threading a cylindrical bar of suitable material, such as brass or steel, and profile 5 of wheel 3 will be curved, with a curvature radius substantially equal to the radius of bar 1.
  • Rod 1 can be mounted on guides of the type indicated by numbers 6 and 7, shown in figures 3 and 4 respectively.
  • Guide 6 can be constituted by a support such as a metal block shaped to form a clamp, fitted with a pair of arms 8 whose shape follows the profile of bar 1 and which surround more than half the length of the perimeter of the bar, such as approximately two-thirds or three-quarters of the perimeter, so as to retain the bar in its seating.
  • a notch 9 which allows the arms to be tightened, for example with an Allen screw 10 or the like, so as to bring the inner surface of arms 8 into contact with the outer surface of bar 1, or to clamp the former onto the latter.
  • bar 1 can slide in the guides constituted by these supports 6, and the ends of the bar can be fitted with stop means constituted, for example, by clamp elements similar to supports 6, but with a thread corresponding to that of the bar on the inner surface of the arms so that they can be secured tightly around the bar.
  • said bar can be secured on one side with a nut which enables it to be placed under traction, so as to adjust the pitch micrometrically by exploiting the elasticity of the material.
  • Figure 4 shows another actuator according to the invention, wherein the base of support 7 contains a seating for a screw 12 which enables it to be attached to the structure of a machine, for example.
  • the actuator according to the invention offers numerous advantages.
  • the toothing is helical, is it is much quieter than conventional rack-and-pinion actuators, despite its considerably lower cost.
  • the possibility of making the rods by threading a cylindrical bar means that rods up to several metres long can be manufactured, without any increase in costs.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Reciprocating, Oscillating Or Vibrating Motors (AREA)
  • Vehicle Body Suspensions (AREA)
  • Transmission Devices (AREA)
EP04000714A 2003-01-29 2004-01-15 Linear actuator comprising a worm gear Withdrawn EP1443247A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITPC20030002 2003-01-29
ITPC20030002 ITPC20030002U1 (it) 2003-01-29 2003-01-29 Attuatore lineare a spostamento veloce

Publications (1)

Publication Number Publication Date
EP1443247A1 true EP1443247A1 (en) 2004-08-04

Family

ID=27638592

Family Applications (1)

Application Number Title Priority Date Filing Date
EP04000714A Withdrawn EP1443247A1 (en) 2003-01-29 2004-01-15 Linear actuator comprising a worm gear

Country Status (2)

Country Link
EP (1) EP1443247A1 (it)
IT (1) ITPC20030002U1 (it)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006024183A1 (de) * 2004-09-02 2006-03-09 Belimo Holding Ag Linearantrieb

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1305188A (it) * 1969-06-14 1973-01-31
US4796479A (en) * 1987-06-30 1989-01-10 Wisecarver Martin L Clutch mechanism
US5186068A (en) * 1991-06-20 1993-02-16 Peerless-Winsmith, Inc. Gear reducer with backlash eliminator
US5373753A (en) * 1993-02-25 1994-12-20 Toyomasa; Hiroshi Power transmission device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1305188A (it) * 1969-06-14 1973-01-31
US4796479A (en) * 1987-06-30 1989-01-10 Wisecarver Martin L Clutch mechanism
US5186068A (en) * 1991-06-20 1993-02-16 Peerless-Winsmith, Inc. Gear reducer with backlash eliminator
US5373753A (en) * 1993-02-25 1994-12-20 Toyomasa; Hiroshi Power transmission device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006024183A1 (de) * 2004-09-02 2006-03-09 Belimo Holding Ag Linearantrieb

Also Published As

Publication number Publication date
ITPC20030002V0 (it) 2003-01-29
ITPC20030002U1 (it) 2004-07-30

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